关键词: 苔藓, 灌丛, 持水性能, 祁连山

Abstract: Water holding capacity of mosses is one of important indicators to measure moisture-holding capacity of woodland，and it plays an important role in studying ecological and hydrological process for forest ecosystem. The research on water holding capacity of moss under shrubs is very important and necessary for understanding the impact of hydrological characteristics of moss and revealing the mechanism of hydrological function of moss due to widespread shrubs which account for 68% of the whole forest area of the Qilian Mountains，Gansu Province，China. Based on field and laboratory experiments in August 2012，taken the five typical mosses under alpine shrubs：Potentilla fruticosa，Salix cupularis，Hippophae rhamnoides，Salix oritrepha，and Caragana jubata in the Qilian Mountains as test objects，water holding capacity of mosses under shrubs were investigated and analyzed. The results indicate that the largest stock volume of the mosses is S. oritrepha，followed by P. fruticosa，C. jubata，S. cupularis and H. rhamnoides shrub. Shrub vegetation types and structural features are key factors that affect moss stock volume. The maximum water holding capacity per unit area of mosses under shrubs varies from 13 790 g·m^-2 to 18 980 g·m^-2. The maximum water holding capacity belongs to C. jubata shrub and then followed by H. rhamnoides，S. cupularis，S. oritrepha，and P. fruticosa shrub. The mosses could absorb water that exceeds its own weight from 386.94% to 782.51% times. The maximum water holding rate belongs to P. fruticosa shrub，and then followed by S. oritrepha，H. rhamnoides，C. jubata and S. cupularis shrub. Mosses under alpine shrub have strong water absorption capacity. Water holding capacity increases with time immersed in water in laboratory experiment. It shows a sharp increase when time immersed in water is less than 0.5 hours，and become stable values while more than 6 hours except [S. oritrepha] shrub. All water absorption of moss keeps stable after more than 12 hours immersing. The relationship between water holding capacity and time immersed in water could be fitted with logarithmical curve. Water absorption rates of mosses decline rapidly in the first 2 hours，and then decrease slowly from 2 to 6 hours; subsequently the rates become saturated when mosses are immersed after more than 6 hours in water. Water absorption rates of moss under C. jubata show the most dramatic decline with the time immersed in water. Water absorption rates of mosses under all shrubs decrease according to power function cure with time immersed in water. There are several factors influencing the water holding capacity of mosses under shrubs，such as interception of light and precipitation，pastoral activities，vegetation structure and succession，etc. The most important factor is canopy structure of alpine shrubs. The present research emphasizes the important role of moss in studying storage water capacity in alpine shrub ecosystem. Research results can provide useful information for ecological and hydrological function in alpine areas，and valid parameters and empirical formula for eco-hydrological model in different scale.

Key words: mosses, alpine shrub, water holding capacity, Qlian Mountains